Measuring and recording the current profile depth of tires is important primarily in fleet management in order to obtain an overview of the running performance and the wear behavior of the tires which are used on the individual vehicles. However, measuring and recording the profile depth is important for individuals too. In addition to the use of profile depth measuring devices, indicators which are integrated in the tread of the tires have also become well-established. The indicators allow the wear of the tread to be established with the aid of incisions of different depth in the tread. Conventional wear indicators in the tread of a tire are also designed as raised portions on the profile base of a circumferential groove. If this raised portion reaches the level of the surface of the tread, the legally prescribed minimum profile depth has been reached. However, the vehicle owner or vehicle user can only roughly estimate the current profile depth. Furthermore, there is a risk of cracks being produced in the circumferential grooves in the case of wear indicators of this kind.
U.S. Pat. No. 4,226,274 B discloses designing a wear indicator in the form of a narrow insert which is a different color to the surrounding rubber and runs over the tread circumference. This insert has a specific cross section, with the result that the insert becomes narrower as wear increases. U.S. Pat. No. 6,883,567 B discloses making incisions in the tread. The incisions either become shorter or longer as wear increases. A CCD camera is used to evaluate or determine the tread wear. The CCD camera creates images of the incisions and passes on the data to a processor which calculates the current profile depth by evaluating the dimensions of the incision and comparing them with the stored dimensions of the original incision. This apparatus requires a large amount of equipment and can be operated only in a stationary state.